Pin golangci-lint to commit c0d3ddc9cf3faa61a4e378e879ece580256d76e5
(v2.12.2) in Dockerfile and script/bootstrap.
Replace .golangci.yml with a v2-schema migration of the canonical
config, produced with golangci-lint migrate (owner-authorized; the
same file becomes the new org-wide canonical via a prompts-repo PR).
Lint settings now live under linters.settings, so the lll, funlen,
cyclop, and dupl thresholds are actually applied. The deprecated
gomodguard linter is disabled in favor of gomodguard_v2, resolving
the v2.12 deprecation warning. Deliberate delta from the migrate
output: the gci formatter is not enabled because its default two-group
import ordering conflicts with the repo's stdlib/third-party/local
import style that script/fmt (gofmt + goimports) produces.
Fix all findings surfaced by the now-active thresholds:
- goconst: shared constants for repeated status, priority, and DNS
fixture strings in watcher.go and the notify, state, and watcher
tests
- dupl: consolidate duplicated ntfy/slack HTTP-error tests and
SendNotification endpoint-error tests behind shared helpers
- lll: wrap long test table entries and comments; shorten one inline
nolint justification
